The method was printed in old BCM mag I have done several times. Will try to find referance to article. I still need article to redo -cost about $30 and no power limits. Haven't had one break down. Bob

The BCM article on the use of relays to "build" a 5 to 4 (and 24V to 12V converter) is in the March 2009 issue. I compiled the article from information furnished by Craig Shepard, Sean Welsh, and Jack Conrad.

Craig used to fabricate the systems for others. Don't know if he still does.

He used MCI relays. The rest of us used Mini ISO which are easier to find and less expensive. Because of possible problems with coil collapse current, it is strongly recommended that relays with diodes (or external diodes between the coil trigger leads) be used.

I had several "commercial" converters fail in a very short period. For about the same price, the relay system is almost bullet proof and has served me well for several years.

I can personally vouch for Craig's system. We have one in the back of our MC9, used it to properly power our taillights, brake lights, turn signals etc.. Absolutely 0 problems - worked like a charm, cost was reasonable, came with setup instructions.

Craig built one for us about 1/2 year or so ago. Not sure if he is regularly building them or just on a special case. Probably best to directly reach out to him to see.

Yes, I do still occasionally build them on an on-demand basis. In fact, I just shipped one earlier this week. I don't build these as a business, and do not actively market them. I have a blurb about them in the above referenced webpage on my bus site. People like Jim and Phil provide word of mouth advertising, and I build them on-demand as necessary. I've made the schematic available on the website should anyone want to build their own. Some people prefer to have me buildit for them, which is why I offer the service. I just ask that my design not be used for commercial purposes (i.e. don't build andsell them).

As indicated, I use MCI compatible relays, and I add external diodes to all the coils. I also use 10 amp auto-reset circuit breakerson the outputs.

I don't keep pre-built units on the shelf any more, but I have all the components and can put one together in a short time. Usually,I quote 3-4 days, but in reality, when someone says they want one, it's finished and ready to ship before their check arrives. I was looking over my records the other day, and over the years, I've built more than 25 of these things, and I've never had a complaint or heard of anyone having a failure. As far as I know, the only problem ever experienced with one of my units was my own. A few years ago I had a relay start sticking on me. I don't recall if I replaced it or just smacked it and it started working again, but that was about 3 years ago, and hasn't been a problem since.